• upgrade from squeeze-kerneltest.img.xz
• development system is running deb8

cd /var/lib/kernel-autobuild/00-resources
cp squeeze-kerneltest.img.xz wheezy-kerneltest.img.xz
xz -d wheezy-kerneltest.img.xz
->
  Disk wheezy-kerneltest.img: 1 GiB, 1073741824 bytes, 2097152 sectors
  Units: sectors of 1 * 512 = 512 bytes
  Sector size (logical/physical): 512 bytes / 512 bytes
  I/O size (minimum/optimal): 512 bytes / 512 bytes
  Disklabel type: dos
  Disk identifier: 0x000a4fa9

  Device                 Boot   Start     End Sectors   Size Id Type
  wheezy-kerneltest.img1 *         63 1654694 1654632 807.9M 83 Linux
  wheezy-kerneltest.img2      1654695 2088449  433755 211.8M 82 Linux swap / Solaris

CMD=" kvm -M pc -net nic,macaddr=66:66:66:66:66:15,model=rtl8139
      -net tap,script=/etc/qemu-ifup
      /var/lib/kernel-autobuild/00-resources/wheezy-kerneltest.img
      -name kernel-autobuild-kerneltest
      -k de
      -curses
      -pidfile /tmp/kvm.pid
      -monitor unix:/tmp/kvm-socket,server,nowait
      -vnc 127.0.0.1:15
"
$CMD

apt-get update
apt-get upgrade
cat << EOF > /etc/apt/sources.list
deb http://ftp.debian.org/debian/ wheezy main contrib non-free
deb http://ftp.debian.org/debian/ wheezy-updates main contrib non-free
deb http://ftp.debian.org/debian/ wheezy-proposed-updates main contrib non-free
EOF
apt-get update
apt-get upgrade
apt-get dist-upgrade
apt-get clean
rm /var/log/* /var/log/*/*
sed -i 's/squeeze/wheezy/g' /etc/hosts /etc/hostname
HISTFILESIZE=0 HISTSIZE=0
reboot
HISTFILESIZE=0 HISTSIZE=0
dpkg -l | grep squeeze | xargs apt-get -y purge
dpkg -l | grep ^r      | xargs apt-get -y purge
dd if=/dev/zero of=/tmp/null bs=1M ; rm /tmp/null
reboot

halt

pxz wheezy-kerneltest.img
->
    -rw-r--r-- 1 root root  99M Oct 11  2012 squeeze-kerneltest.img.xz
    -rw-r--r-- 1 root root 159M Oct 24 10:11 wheezy-kerneltest.img.xz